1. Field of the Invention
The invention relates to a semiconductor package and a method of fabricating the same, and in particular, to a ball grid array package, and a method of fabricating the same.
This application is a counterpart of Japanese Patent Application, Serial Number 243274/2001, filed Aug. 10, 2001, the subject matter of which is incorporated herein by reference.
2. Description of the Related Art
A conventional method of fabricating a semiconductor package is disclosed in Japanese Patent Laid-Open No. 274367/1999. The conventional semiconductor package comprises a lead frame on which solder balls are formed, a first molding die member in which cavities for receiving the solder balls are formed, and a second molding die member to be engaged with the first molding die member. The conventional method of fabricating the semiconductor package comprises the steps of disposing a plastic layer in each of the cavities of the first molding die member, disposing the solder ball on the plastic layer, causing the solder ball to be deformed on the plastic layer by engaging the first molding die member with the second molding die member, and filling up a gap between the first molding die member and the second molding die member with a sealing resin, thereby fabricating the semiconductor package. Further, in the step of sealing, the sealing resin inside the respective cavities is prevented from covering the surface of the respective solder balls.
With the conventional method of fabricating the conventional semiconductor package as described above, however, in order to ensure electrical connection between respective leads and the respective solder balls, the respective solder balls are connected beforehand to the respective leads of the lead frame, corresponding thereto, prior to the step of the sealing with the resin.
As a result of such work for connecting the respective solder balls with the respective leads, both are connected with each other with certainty. However, since such connection of the solder balls is implemented through fusion of the solder balls by heating, the surfaces of the solder balls get oxidized when the solder balls are exposed to a high temperature. Furthermore, with the conventional method as described above, the respective solder balls are subjected to heating through the intermediary of both the first and second molding die members again in the step of the sealing with the resin as described above. As a result of such heating applied twice, the respective solder balls serving as respective connection terminals are prone to growth of an oxide film on the surface thereof, and such growth of the oxide film is detrimental to reliable and easy soldering work between the respective solder balls and printed wiring when mounting the semiconductor package on, for example, a printed wiring board. Accordingly, in order to enable the reliable and easy soldering work to be implemented, there are times when a step of removing the oxide film from the surface of the respective solder balls is required prior to the soldering work.
Further, with the conventional method as described above, there is the need for using a special type plastic layer free from a risk of bonding with a resin material and the solder balls in order to prevent intrusion of the resin material into a gap formed between the respective cavities of the first molding die member and the respective solder balls, and further, the steps of disposing the special type plastic layer inside the respective cavities, and peeling off the same are required, resulting in an increase in material cost, and complexity in a fabrication process, and thereby raising a risk of an increase in fabrication cost.